Organic solar cells with thin film form are light, flexible, transparent, low cost, customizable, and applicable to non-vacuum all-solution large-area printing and coating process. In recent year, they play an important role in the application of renewable energy. The trend of their development attracts attention by academics and the industry.
Currently, for preparing an organic solar cell module having a serial structure, as shown in FIG. 1, a plurality of organic solar cells are disposed on the substrate 90. Each cell includes a stack structure comprising a transparent conductive layer 91, an electron transport layer 92, an active layer 93, a hole transport layer 94, and a metal layer 95. While stacking the electron transport layer 92, the active layer 93, the hole transport layer 94, and the metal layer 95, each layer is shifted for filling the gaps in the transparent conductive layer 91 and connecting multiple cells in series by enabling the transparent conductive layer 91 to contact the metal layer 95.
The effective power generating area AEff of the organic solar cells having such kind of serial structure is shown in the figure. The effective area is influenced by the gap in the transparent conductive layer 91. A large portion of the light receiving area of the organic solar cells is wasted in the gaps not capable of generating power and thus limiting the power generated per unit of total area. In order to avoid waste in the power generating area of the module, the gaps in the transparent conductive layer 91 are shrunk as small as possible. Nonetheless, the shifts of the layer are accordingly extremely small, leading to difficulty in preparation. In particular, when large-area solution printing processes, such as spray coating, inkjet printing, and roll-to-roll printing, are applied, the accuracy of the shifts of the layers is hard to control. A very small error in shift might destroy the serial relation of the cells and affect the power generating efficiency.
Accordingly, the present invention provides a novel serial module of organic solar cell, which improves the power per unit area generated by the power generating module. Beside, it also reduces the difficulty in large-area solution printing processes. Thereby, the present invention facilitates commercialization and promotion of organic solar cells.